PC-O 42:4—a biomarker for visceral adiposity

ABSTRACT

The present invention generally relates to the field of biomarkers. In particular, the present invention relates to biomarkers such as PC-O 42:4 that can be used, for example for detecting and/or quantifying visceral adiposity and/or changes in visceral adiposity. This biomarker may also be used to diagnosing the effect of a change in lifestyle on visceral adiposity in a subject.

The present application is a continuation of PCT/EP2013/061877, filedJun. 10, 2013, which application claims priority to European ApplicationNo. 12171573.4, filed Jun. 12, 2012, the disclosures of which are herebyincorporated by reference in their entirety for all purposes.

The present invention generally relates to the field of biomarkers. Inparticular, the present invention relates to biomarkers such as1-O-alkyl-2-acylglycerophosphocholine (PC-O) 42:4 that can be used, forexample for detecting and/or quantifying visceral adiposity and/orchanges in visceral adiposity. This biomarker may also be used fordiagnosing the effect of a change in lifestyle on visceral adiposity ina subject.

The continuous rise in the overweight and obesity epidemic, particularlyamong children, has made the deciphering of their associated genome andmetabolome phenotypes become one of the greatest public healthchallenges. Although malnutrition and obesity, as defined by body massindex (BMI), impose a substantial toll on life expectancy, it is clearthat BMI has considerable limitations in the assessment of bodycomposition and lack sensitivity for assessing disease risks (Dulloo, A.G., et al. (2010) Int. J. Obes. (Lond) 34 Suppl 2, S4-17. Dullo et al.recently reviewed recent advances in concepts about health risks relatedto body composition phenotypes, including (i) the partitioning of BMIinto a fat mass (FM) index (FM/H2) and a fat-free-mass (FFM) index(FFM/H2), (ii) the partitioning of FFM into organ mass and skeletalmuscle mass, (iii) the partitioning of FM into hazardous fat andprotective fat and (iv) the interplay between adipose tissueexpandability and ectopic fat deposition within or around organs/tissuesthat constitute the lean body mass (Dulloo, A. G., et al. (2010) Int. J.Obes. (Lond) 34 Suppl 2, S4-17)

During the last decades, numerous investigations using state of the arttechnologies have identified genes and transcription factors associatedwith fat storage and obesity (Viguerie, N., et al. (2005) Diabetologia48, 123-131; Viguerie, N., et al. (2005) Biochimie 87, 117-123;Sorensen, T. I. et al. (2006) PLoS. Clin. Trials 1, e12; Klannemark, M.,et al. (1998) Diabetologia 41, 1516-1522; Clement, K. et al. (2007) J.Intern. Med. 262, 422-430), genetic inheritability (Teran-Garcia, M. Etal. (2007) Appl. Physiol Nutr. Metab 32, 89-114) and have suggested aninfluence of the human gut microbiota on obesity incidence (Backhed, F.,et al. (2007) Proc. Natl. Acad. Sci. U.S.A. 104, 979-984; Ley, R., etal. (2006) Nature 444, 1022-1023; Turnbaugh, P., et al. (2006) Nature444, 1027-1031).

However, under similar obesogenic and diabetogenic environments, manyindividuals still remain metabolically healthy and resistant toadiposity-associated cardiovascular disease (CVD) risks. In addition tothe awareness that disease risks associated with obesity may not beuniform (Wildman, R. P., et al., (2008) Arch. Intern. Med. 168,1617-1624), an increasing number of individuals with normal weight (bodymass index, BMI<25) express cardiometabolic abnormalities previouslythought to be specific to overweight and obese states. Most recentevidence indicates how regio-specific body composition may determineindividual predisposition to metabolic disease, with body fat and inparticular visceral fat distribution being correlated with increasedrisk of cardiometabolic disorders, diabetes, hypertension, nonalcoholicfatty liver disease, and mortality.

Visceral adiposity is been clinically monitored using waist and hipmeasurements, (e.g. >0.9 for men and >0.85 for women, which howeversuffers from similar limitations especially in obese populations. Goldstandard imaging technologies, including magnetic resonance imaging(MRI) and computed tomography (CT) scans, now generate regio-specificand highly accurate quantification of visceral fat depots. However, theassessment of the metabolism associated with visceral fat remainsparticularly challenging due to the lack of non-invasive, fast andreliable biomarkers that can be used in epidemiological studies and dueto limitations of conventional analytical approaches that are not suitedfor the holistic analysis of the metabolism.

Excess fat stored in the trunk or android regions could be metabolicallyless healthy than fat stored in the gynoid area, with insulin resistanceas a key causal mechanism. Therefore, patient stratification isnecessary for personalized nutritional and therapeutical management, yetits application is challenged when subjects have similar waist-to-hippratio and access to imaging facilities is limited. There is thereforeand urgent need for biomarkers that allow assessing the presence ofvisceral fat, the metabolism associated with visceral fat and/or changestherein in a simple and reliable way.

The present inventors have addresses this need.

It was therefore the objective of the present invention to improve thestate of the art and to provide biomarkers that meet the objective ofthe present invention and/or that allow overcoming at least one of thedisadvantages of the present state of the art.

To identify appropriate biomarkers the inventors have used a metabonomicapproach.

Metabonomics is considered today a well-established system approach tocharacterize the metabolic phenotype, that comprises the influence ofvarious factors such as environment, drugs, dietary, lifestyle,genetics, and microbiome factors. Unlike gene expression and proteomicdata that indicate the potential for physiological changes, metabolitesand their dynamic concentration changes within cells, tissues andorgans, represent the real end-points of physiological regulatoryprocesses.

Recently, metabolomics and lipidomics-based discoveries have beenaccelerating our understanding of disease processes, and will providenovel avenues for prevention and nutritional management of thesub-clinical disorders associated to metabolic syndrome.

The present inventors have aimed to provide a comprehensive metabolicphenotype of a regio-specific body composition: visceral adiposity. Thishas allowed the identification of biological markers specific ofvisceral adiposity.

In the present study, the metabolism associated with visceral adipositywas investigated in a cohort of 40 healthy obese women using themeasurement of various metabolic endpoints in combination with in vivoquantification of body composition using Dual energy X-rayAbsorptiometry (DXA) and abdominal fat distribution using computerizedtomography (CT) scan.

Using a combination of proton nuclear magnetic resonance (¹H NMR)spectroscopy and targeted LC-MS/MS profiles of plasma and 24 hour urinesamples collected overtime, the inventors have identified novelmetabolic biomarkers of visceral fat distribution in this well definedobese cohort with different visceral fat deposition patterns.

As such, the inventors have identified a novel biomarker, PC-O 42:4.

PC-O is 1-O-alkyl-2-acylglycerophosphocholine.

The individual lipid species were annotated as follows: [lipid class][total number of carbon atoms]:[total number of double bonds]. Forexample, PC 34:1 reflects a phosphatidylcholine species comprising 34carbon atoms and 1 double bond.

PC-O 42:4 is therefore 1-O-alkyl-2-acylglycerophosphocholine 42:4.

The inventors have further found that PC-O 42:4 may be used as abiomarker for detecting and/or quantifying visceral adiposity and/orchanges in visceral adiposity. This diagnostic method is practisedoutside of the human or animal body.

This detection and/or quantification of the biomarker may be carried outin a body liquid. The body liquid may be blood, blood plasma, bloodserum or urine, for example.

Typically, the biomarker detection and/or quantification step is carriedout in a body fluid sample that was previously obtained from the subjectto be tested.

Visceral fat is also known as abdominal fat, organ fat orintra-abdominal fat, and is located inside the abdominal cavity inbetween organs.

Visceral fat may be composed of several adipose depots, includingmesenteric, epididymal white adipose tissue (EWAT), and perirenaldepots, as well as epicardial adipose tissue and fat around liver andstomach. Typically, fat in the abdomen is mostly visceral, oftenresulting in the famous “beer belly”.

Too much visceral fat results in central obesity, which in turn islinked to cardiovascular disorders, type 2 diabetes, insulin resistance,or inflammatory diseases, for example. These are examples of disordersassociated with excess visceral fat.

The present invention relates also to a method of diagnosing visceraladiposity in a subject, comprising determining the level of1-O-alkyl-2-acylglycerophosphocholine (PC-O) 42:4 in a body fluid samplepreviously obtained from a subject to be tested, and comparing thesubject's PC-O 42:4 level to a predetermined reference value, whereinthe predetermined reference value is based on an average PC-O 42:4 levelin the same body fluid in a control population, and wherein a decreasedPC-O 42:4 level in the sample compared to the predetermined referencevalue indicates an increased visceral adiposity.

Visceral adiposity may include mesenteric, epididymal white adiposetissue and/or perirenal fat, as well as epicardial adipose tissue andfat around liver and stomach.

The body fluid may be blood, blood serum, blood plasma, or urine, forexample.

Blood serum and/or blood plasma have the advantage that the signal tonoise ratio for the biomarker to be tested is particularly high.

Urine has the advantage that the body fluid sample can be obtainednon-invasively.

Irrespective of the chosen body fluid, the method of the presentinvention has the advantage that obtaining such body fluids from asubject is a well established procedure.

The actual diagnosis method is then carried out in a body fluid sampleoutside the body.

The level of PC-O 42:4 in the sample can be detected and quantified byany means known in the art. For example, mass spectroscopy, e.g,UPLC-ESI-MS/MS, may be used. Other methods, such as other spectroscopicmethods, chromatographic methods, labeling techniques, or quantitativechemical methods may be used as well.

Ideally, the PC-O 42:4 level in the sample and the reference value aredetermined by the same method.

The predetermined reference value may be based on an average PC-O 42:4level in the tested body fluid in a control population. The controlpopulation can be a group of at least 3, preferably at least 10, morepreferred at least 50 people with a similar genetic background, age andaverage health status.

The control population can also be the same person, so that thepredetermined reference value is obtained previously from the samesubject. This will allow a direct comparison of the effect of a presentlifestyle to a previous lifestyle on visceral adiposity, for example,and improvements can be directly assessed.

The determination of visceral fat adiposity allows concluding on thepresence of visceral fat adiposity and on the risk to acquire associateddisorders.

The subject matter of the present invention also relates to a method ofdiagnosing a change in visceral adiposity in a subject, comprisingdetermining the level of PC-O 42:4 in a body fluid sample previouslyobtained from a subject to be tested, and comparing the subject's PC-O42:4 level to a predetermined reference value, wherein the predeterminedreference value is based on a PC-O 42:4 level in the same body fluidobtained from the same subject previously, and wherein a decreased PC-O42:4 level in the sample compared to the predetermined reference valueindicates increased visceral adiposity.

This method allows following the build-up or reduction of visceral fatover time, and consequently allows conclusions on increased or decreasedrisks to develop disorders associated with visceral adiposity.

This has for example the advantage that immediate results are available,long before an actual increase or decrease of visceral fat can bedetermined. This is in particular good for the motivation of people thataim to reduce visceral fat. Notably, the reduction of visceral fat is adifficult task often requiring intensive exercise. Ohkawara et al.suggests at least 10 metabolic equivalent of task (MET)-hours per weekof aerobic exercise are required for effective visceral fat reduction(Ohkawara, K.; et al., (2007), International journal of obesity (2005)31 (12): 1786-1797).

The present invention also relates to a method of diagnosing the effectof a change in lifestyle on visceral adiposity in a subject, comprisingdetermining the level of PC-O 42:4 in a body fluid sample previouslyobtained from a subject to be tested, and comparing the subject's PC-O42:4 level to a predetermined reference value, wherein the predeterminedreference value is based on a PC-O 42:4 level in the same body fluidobtained from the same subject previously, and wherein a decreased PC-O42:4 level in the sample compared to the predetermined reference valueindicates a positive effect of the change in lifestyle on visceraladiposity.

This method has the effect that it allows monitoring the effect oflifestyle changes on visceral fat mass and on risks for associateddisorders.

The change in lifestyle may be any change, such as a new job, adifferent stress level, a new relationship, increases or decreases inphysical activity, and/or a change in overall wellbeing.

For example, the change in lifestyle may be a change in the diet.

The change in diet may be an increase or decrease in carbohydrate, lipidand/or protein content. It may be the switch to a different regionaldiet, such as the Mediterranean diet, for example. It may also be achange in total caloric intake.

As such the method of the present invention may be used to test theeffectiveness of a new nutritional regimen, of nutritional productsand/or of medicaments.

Nutritional products may be for example products that claim to have aneffect on body fat, weight management and/or visceral fat.

Typically, nutritional products may be food products, drinks, pet foodproducts, food supplements, nutraceuticals, food additives ornutritional formulas.

For example, the change in the diet may be the use of at least onenutritional product that was previously not consumed or consumed indifferent amounts.

As such, the method of the present invention may be used to test theeffectiveness of a new nutritional regimen and/or a nutritional product.

PC-O 42:4 may be used as the only marker for the purpose of the presentinvention.

While PC-O 42:4 as sole marker is effective as a tool for the diagnosismethod of the present invention, the quality and/or the predictive powerof said diagnosis will be improved, if the diagnosis relies on more thanjust one marker.

Hence one or more other markers for diagnosing visceral adiposity and/orthe risk for associated disorders in a subject may be used incombination with PC-O 42:4.

The inventors were surprised to see that also other biomarkers can beused to detect diagnosing visceral adiposity and/or the risk forassociated disorders.

As such the inventors have identified that decreased body fluidconcentrations of PC-O 44:6, PC-O 44:4, PC-O 42:4, PC-O 40:4, and/orPC-O 40:3; and/or increased body fluid concentrations of tyrosine and/orglutamine allow diagnosing an increase in visceral fat amounts and/or anincreased risk for developing disorders associated with excess visceralfat.

Conversely, increased body fluid concentrations of PC-O 44:6, PC-O 44:4,PC-O 42:4, PC-O 40:4, and/or PC-O 40:3; and/or decreased body fluidconcentrations of tyrosine and/or glutamine allow diagnosing a decreasein visceral fat amounts and/or a reduced risk for developing disordersassociated with excess visceral fat.

The methods of the present invention may, hence, further comprise thesteps of determining the level of at least one further biomarkerselected from the group consisting of glutamine, and/or tyrosine, PC-O44:4, PC-O 44:6, PC-O 40:4, and/or PC-O 40:3 in the body fluid sample,and comparing the subject's level of at least one of glutamine,and/ortyrosine, PC-O 44:4, PC-O 44:6, PC-O 40:4, and/or PC-O 40:3 to apredetermined reference value, wherein the predetermined reference valueis based on average glutamine, tyrosine, PC-O 44:4, PC-O 44:6, PC-O40:4, and/or PC-O 40:3 levels in a body fluid sample of a normal healthycontrol population, or on glutamine, tyrosine, PC-O 44:4, PC-O 44:6,PC-O 40:4, and/or PC-O 40:3 levels in the same body fluid obtained fromthe same subject previously, and wherein an increased glutamine and/ortyrosine level and/or a decreased PC-O 44:6, PC-O 44:4, PC-O 42:4, PC-O40:4, and/or PC-O 40:3 level in the body fluid sample compared to thepredetermined reference values indicates an increased visceraladiposity.

The method of the present invention may comprise the assessment of atleast 2, at least 3, at least 4, at least 5, at least 6, or at least 7biomarkers.

For example, PC-O 42:4 may be assessed together with PC-O 44:4.

PC-O 42:4 may also be assessed together with PC-O 44:6.

PC-O 42:4 may also be assessed together with PC-O 40:4.

PC-O 42:4 may also be assessed together with PC-O 40:3.

PC-O 42:4 may also be assessed together with PC-O 44:4 and PC-O 44:6.

PC-O 42:4 may also be assessed together with PC-O 44:4, PC-O 44:6, andPC-O 40:4.

PC-O 42:4 may also be assessed together with PC-O 44:4, PC-O 44:6, andPC-O 40:3.

PC-O 42:4 may also be assessed together with PC-O 44:4, PC-O 44:6, PC-O40:3, and PC-O 40:4.

PC-O 42:4 may also be assessed together with PC-O 44:4, PC-O 44:6, PC-O40:3, PC-O 40:4, and glutamine.

PC-O 42:4 may also be assessed together with PC-O 44:4, PC-O 44:6, PC-O40:3, PC-O 40:4, glutamine and tyrosine.

The advantage of assessing more than one biomarker is that the morebiomarkers are evaluated the more reliable the diagnosis will become.If, e.g., more than 1, 2, 3, 4, 5, 6, or 7 biomarkers exhibit theelevations or decreases in concentration as described above, thepredictive power for the presence or absence and the degree of visceralobesity as well as the risk for associated disorders is stronger.

In accordance with this the inventors have identified even furtherbiomarkers that can be used to predict visceral adiposity and the riskto develop associated disorders.

For example, it was found that increased concentrations ofphenylalanine, Leucine, Isoleucine, palmitoylcarnitine (C16),caproylcarnitine (C10) octenoylcarnitine (C8:1)lysophospatidylcholine(LPC) 24:0, phosphatidylcholine (PC)PC 30:0, and/or PC 34:4 in bodyfluids or decreased concentrations of PC-O 34:1, PC-O 34:2, PC-O 36:2,PC-O 36:3, PC-O 40:6, PC-O 42:2, PC-O 42:3, PC-O 44:3, PC-O 44:5, PC42:0, and/or PC 42:2 in body fluids compared to corresponding referencevalues previously obtained indicates an increased visceral adiposity andan increased risk for associated disorders.

PC is phosphatidylcholine. LPC is lysophospatidylcholine. C is acylcarnitine.

Conversely, decreased concentrations of phenylalanine, Leucine,Isoleucine, C10 (decanoyl carnitine), C16 (Palmitoylcarnitine), C8:1(Octenoyl-Carnitine) LPC 24:0, PC 30:0, and/or PC 34:4 in body fluids orincreased concentrations of PC-O 34:1, PC-O 34:2, PC-O 36:2, PC-O 36:3,PC-O 40:6, PC-O 42:2, PC-O 42:3, PC-O 44:3, PC-O 44:5, PC 42:0, and/orPC 42:2 in body fluids compared to corresponding reference valuespreviously obtained indicates a decreased visceral adiposity and areduced risk for associated disorders.

Hence, the methods of the present invention may, further comprise thesteps of determining the level of at least one further biomarkerselected from the group consisting of phenylalanine, Leucine,Isoleucine, C10 (decanoyl carnitine), C16 (Palmitoylcarnitine), C8:1(Octenoyl-Carnitine), LPC 24:0, PC 30:0, PC 34:4, PC-O 34:1, PC-O 34:2,PC-O 36:2, PC-O 36:3, PC-O 40:6, PC-O 42:2, PC-O 42:3, PC-O 44:3, PC-O44:5, PC 42:0, and/or PC 42:2 in the body fluid sample, and comparingthe subject's level of at least one of phenylalanine, Leucine,Isoleucine, C10, C16, C8:1, carnitine, LPC 24:0, PC 30:0, PC 34:4, PC-O34:1, PC-O 34:2, PC-O 36:2, PC-O 36:3, PC-O 40:6, PC-O 42:2, PC-O 42:3,PC-O 44:3, PC-O 44:5, PC 42:0, and/or PC 42:2 to a predeterminedreference value, wherein the predetermined reference value is based onaverage phenylalanine, Leucine, Isoleucine, C10, C16, C8:1, carnitine,LPC 24:0, PC 30:0, PC 34:4, PC-O 34:1, PC-O 34:2, PC-O 36:2, PC-O 36:3,PC-O 40:6, PC-O 42:2, PC-O 42:3, PC-O 44:3, PC-O 44:5, PC 42:0, and/orPC 42:2 levels in a body fluid sample of a normal healthy controlpopulation, or on phenylalanine, Leucine, Isoleucine, C10 (decanoylcarnitine), C16 (Palmitoylcarnitine), C8:1 (Octenoyl-Carnitine), LPC24:0, PC 30:0, PC 34:4, PC-O 34:1, PC-O 34:2, PC-O 36:2, PC-O 36:3, PC-O40:6, PC-O 42:2, PC-O 42:3, PC-O 44:3, PC-O 44:5, PC 42:0, and/or PC42:2 levels in the same body fluid obtained from the same subjectpreviously, and wherein an increased phenylalanine, Leucine, Isoleucine,C10, C16, C8:1, carnitine, LPC 24:0, PC 30:0, and/or PC 34:4 level inthe body fluid and/or a decreased PC-O 34:1, PC-O 34:2, PC-O 36:2, PC-O36:3, PC-O 40:6, PC-O 42:2, PC-O 42:3, PC-O 44:3, PC-O 44:5, PC 42:0,and/or PC 42:2 level in the body fluid sample compared to thepredetermined reference values indicates an increased visceraladiposity.

An increased visceral adiposity increases the risk to develop disordersassociated with excess visceral fat.

Consequently, in the methods of the present invention the degree ofvisceral adiposity may be used as indication for the likelihood todevelop disorders associated with excess visceral fat.

Also, changes in visceral adiposity may be used as indication for anincreased or decreased likelihood to develop disorders associated withexcess visceral fat.

Disorders associated with visceral adiposity are for example cardiometabolic disorders.

Hence, the methods of the present invention may be used to determine therisk to develop cardio metabolic disorders.

Further disorders associated with visceral adiposity are for examplemetabolic deregulations. Typical metabolic deregulations are thefollowing obesity, insulin resistance, Type 2 diabetes, metabolicsyndrome, vascular diseases (hypertension, coronary heart disease),steatohepatitis in metabolic liver disease, lipodystrophies, pulmonaryfunction, inflammatory disorders and other obesity related disorders.

The methods of the present invention can be carried out with anysubject.

Advantageously, the method of the present invention may be carried outon subjects at risk of developing visceral adiposity and/or disordersassociated with visceral adiposity.

For example the methods of the present invention may be to be carriedout with normal, overweight or obese subjects.

“Overweight” is defined for an adult human as having a BMI between 25and 30. “Body mass index” or “BMI” means the ratio of weight in kgdivided by the height in meters, squared. “Obesity” is a condition inwhich the natural energy reserve, stored in the fatty tissue of animals,in particular humans and other mammals, is increased to a point where itis associated with certain health conditions or increased mortality.“Obese” is defined for an adult human as having a BMI greater than 30.

The reference value for PC-O 42:4 and optionally for the otherbiomarkers is preferably measured using the same units used tocharacterize the level of PC-O 42:4 and optionally the other biomarkersobtained from the test subject. Thus, if the level of the PC-O 42:4 andoptionally the other biomarkers is an absolute value such as the unitsof PC-O 42:4 in μmol/l (μM) the reference value is also based upon theunits of PC-O 42:4 in μmol/l (μM) in individuals in the generalpopulation or a selected control population of subjects.

Moreover, the reference value can be a single cut-off value, such as amedian or mean. Reference values of PC-O 42:4 and optionally the otherbiomarkers in obtained body fluid samples, such as mean levels, medianlevels, or “cut-off” levels, may be established by assaying a largesample of individuals in the general population or the selectedpopulation and using a statistical model such as the predictive valuemethod for selecting a positivity criterion or receiver operatorcharacteristic curve that defines optimum specificity (highest truenegative rate) and sensitivity (highest true positive rate) as describedin Knapp, R. G., and Miller, M. C. (1992). Clinical Epidemiology andBiostatistics. William and Wilkins, Harual Publishing Co. Malvern, Pa.,which is incorporated herein by reference.

Skilled artesians will know how to assign correct reference values asthey will vary with gender, race, genetic heritage, health status orage, for example.

As an example the inventors have determined typical reference values inobese adult human subjects and in normal adult human subjects in a bodyfluid such as blood plasma, for example.

Consequently, the predetermined mean reference values for obese subjectsmay be about

-   -   68.71 μM body fluid for tyrosine,    -   662.67 μM body fluid for glutamine,    -   1.47 μM body fluid for PC-O 44:6,    -   0.84 μM body fluid for PC-O 44:4,    -   1.27 μM body fluid for PC-O 42:4,    -   2.65 μM body fluid for PC-O 40:4,    -   1.37 μM body fluid for PC-O 40:3,    -   52.97 μM body fluid for phenylalanine,    -   193.56 μM body fluid for Leucine+Isoleucine,    -   0.19 μM body fluid for C10,    -   0.06 μM body fluid for C16,    -   0.03 μM body fluid for C8:1,    -   0.25 μM body fluid for LPC 24:0,    -   4.18 μM body fluid for PC 30:0,    -   1.11 μM body fluid for PC 34:4,    -   9.84 μM body fluid for PC-O 34:1,    -   11.49 μM body fluid for PC-O 34:2,    -   11.79 μM body fluid for PC-O 36:2,    -   7.20 μM body fluid for PC-O 36:3,    -   3.68 μM body fluid for PC-O 40:6,    -   0.56 μM body fluid for PC-O 42:2,    -   0.89 μM body fluid for PC-O 42:3,    -   0.21 μM body fluid for PC-O 44:3,    -   2.17 μM body fluid for PC-O 44:5,    -   0.56 μM body fluid for PC 42:0,    -   0.22 μM body fluid for PC 42:2.

In normal subjects the predetermined mean reference values may be about

-   -   75.00 μM body fluid for tyrosine,    -   748.27 μM body fluid for glutamine,    -   1.21 μM body fluid for PC-O 44:6,    -   0.50 μM body fluid for PC-O 44:4,    -   1.12 μM body fluid for PC-O 42:4,    -   3.24 μM body fluid for PC-O 40:4,    -   2.10 μM body fluid for PC-O 40:3,    -   49.17 μM body fluid for phenylalanine,    -   197.52 μM body fluid for Leucine+Isoleucine,    -   0.29 μM body fluid for C10,    -   0.09 μM body fluid for C16.    -   0.04 μM body fluid for C8:1,    -   0.77 μM body fluid for LPC 24:0,    -   4.10 μM body fluid for PC 30:0,    -   1.42 μM body fluid for PC 34:4,    -   8.20 μM body fluid for PC-O 34:1,    -   9.26 μM body fluid for PC-O 34:2,    -   12.67 μM body fluid for PC-O 36:2,    -   5.83 μM body fluid for PC-O 36:3,    -   4.45 μM body fluid for PC-O 40:6,    -   0.82 μM body fluid for PC-O 42:2,    -   1.08 μM body fluid for PC-O 42:3,    -   0.22 μM body fluid for PC-O 44:3,    -   1.82 μM body fluid for PC-O 44:5,    -   0.65 μM body fluid for PC 42:0,    -   0.35 μM body fluid for PC 42:2.

The subjects to be tested with the method of the present invention maybe a human or an animal, in particular a mammal, for example. Typicalanimals may be companion animals, such as cats or dogs of farm animals,for example.

Those skilled in the art will understand that they can freely combineall features of the present invention described herein, withoutdeparting from the scope of the invention as disclosed. In particular,features described for the methods of the present invention may beapplied to other methods and to the use of the present invention andvice versa.

Further advantages and features of the present invention are apparentfrom the following Examples and Figures.

Table 1 shows clinical characteristics of the recruited cohort asstratified in four quartiles based on their visceral fat content asassessed by the log ₁₀ value of the intraperitoneal/abdominal fat ratiomeasured by computerized tomography. Values are presented as mean (±SD).ALAT=alanine aminotransferase, ASAT=aspartate aminotransferase, BMI=bodymass index, GGT=gamma-glutamyl transpeptidase, HDL-C=high densitylipoprotein cholesterol, HOMA-IR=homeostasis model assessment of insulinresistance, LDL-C=low density lipoprotein cholesterol, MAP=mean arterialblood pressure, NEFAs=non esterified fatty acids, TG=triglycerides.

Table 2 shows metabolite concentrations presented as mean (±SD) for eachof the four quartiles based on their visceral fat content as assessed bythe log ₁₀ value of the intraperitoneal/abdominal fat ratio measured bycomputerized tomography.

FIG. 1 shows the statistical reconstruction of ¹H NMR blood plasmaprofiles using random forest analysis to identify metabolic patternsassociated with visceral adiposity (as identified with squared boxes).GPCs=glycerophospholipids, PUFAs=polyunsaturated fatty acids,UFAs=unsaturated fatty acids.

FIG. 2 shows metabolite importance and robustness in predicting visceralfat adiposity as assessed by Random forest analysis. Pooled meandecrease in accuracy after n=10000 random forest generations. Highervariable importance corresponds to higher values of pooled mean decreasein accuracy.

FIGS. 3A, 3B and 3C show metabolite differences between high and lowvisceral fat subjects for each selected metabolite. Data are plotted foreach quartile based on their visceral fat content as assessed by the log₁₀ value of the intraperitoneal fat volume measured by computerizedtomography, 1=quartile 1, 2=quartile 2, 3=quartile 3, 4=quartile 4.

EXAMPLES

Subjects and Experimental Design

The clinical trial was an observational study conducted on 40 healthyobese Caucasian women at the Centre Hospitalier Universitaire Vaudois(CHUV, Lausanne, Switzerland). The study protocol was approved by anindependent Ethical Committee located at the CHUV. The participants hada BMI between 28 and 40, aged between 25 and 45 years old, and showed nometabolic disease traits (diabetes type 2, cardiovascular disease ormetabolic syndrome). The resulting biological samples (blood plasma and24 hours urine samples) were stored at −80° C. until metabolomicanalysis.

Body Composition Assessment

Full body scan was performed to determine both abdominal fatdistribution and total body composition. Total body scans were made on aGE Lunar iDXA system (software version: enCORE version 12.10.113) withscan mode automatically determined by the device. For the DXAmeasurement, all subjects were wearing a hospital gown and had all metalartifacts removed. The iDXA unit was calibrated daily using the GE Lunarcalibration phantom. A trained operator performed all scans followingthe operator's manual for patient positioning and data acquisition.During the one-hour appointment, total body scans of each subject wereperformed twice with repositioning between scans. Scans were analyzedwith the enCORE software (version 14.00.207). The ROIs wereautomatically determined by the enCORE software (Auto ROI) for totalbody, arms, legs, trunk, android, and gynoid regions. An experienced DXAoperator also verified and, when indicated, repositioned the ROIplacements (Expert ROI). In addition to iDXA scan, waist and hipmeasurements were performed.

The CT measures were performed on 64 multi-detector CT scanner (VCTLightspeed, GE Medical Systems, Milwaukee, USA). Subjects lied in thesupine position with their arms above their head and legs elevated witha cushion. A single scan (10 mm) of the abdomen is acquired at the levelof L4-L5 vertebrae and analyzed for a cross-sectional area of adiposetissue, expressed in square centimeters. The following acquisitionparameters were used: 120 Kv, 100-200 mA with z-axis dose modulation anda field of view 500 mm. Axial transverse images of 5 mm slice thicknessare reconstructed using a standard kernel. The quantification processuses a semi interactive commercially available algorithm forsegmentation of subcutaneous and intra-abdominal fat on the AdvantageWindow workstation (GE Medical Systems).

Clinical Chemistry

Plasma total, HDL and LDL cholesterol, triglycerides, urates,creatinine, sodium and potassium concentrations, ALAT, ASAT, GGT,glucose, non-esterified fatty acids, insulin and mean arterial bloodpressure (MAP) were determined using routine laboratory methods. Insulinresistance status was assessed as homeostasis model assessment ofinsulin resistance (HOMA-IR) according to the previously describedformula (Mathews et al., 1985): insulin (μU/mL)×glucose (mmol/L)/22.5.

Sample Preparation and ¹H-NMR Spectroscopic Analysis

Heparin blood plasma samples (400 μL) were introduced into 5 mm NMRtubes with 200 μL of deuterated phosphate buffer solution (KH2PO4 with afinal concentration of 0.2M). Deuterium was employed as lockingsubstance. Metabolic profiles were measured on a Bruker Avance III 600MHz spectrometer equipped with an inverse 5 mm cryogenic probe at 300 K(Bruker Biospin, Rheinstetten, Germany). Standard ¹H-NMR one-dimensionalpulse sequence with water suppression (RD=4s), Carr-Purcell-Meiboom-Gill(CPMG) spin-echo sequence with water suppression (RD=4s), anddiffusion-edited sequence (RD=4s) where acquired for each plasma sample.For each one dimensional experiment 32 scans were collected using 98 Kdata points. ¹H-NMR spectra were processed using TOPSPIN (version 2.1,Bruker, Germany) software package prior to Fourier transformation. Theacquired NMR spectra were manually phased and baseline corrected, andreferenced to the chemical shift of the anomeric proton of α-glucose atδ5.2396 for plasma spectra. The assignment of the ¹H-NMR resonances tospecific metabolites was achieved by matching our in-house developed NMRdatabase of pure compounds and using literature data (Fan, T. W. (1996)Progress in Nuclear Magnetic Resonance Spectroscopy 28, 161-219;Nicholson, J. K., et al. (1995) Anal. Chem. 67, 793-811). Metaboliteidentification was confirmed by 2D ¹H-¹H COrrelation SpectroscopY (COSY)(Hurd, R. E. (1990) J. Magn. Reson. 87, 422-428), ¹H-¹H TOtalCorrelation SpectroscopY (TOCSY) (Sax, A. & Davis (1985) J. Magn. Reson.65, 355-360) and ¹H-¹³C Heteronuclear Single Quantum Correlation (HSQC)(Bodenhausen, G. & Ruben (1980) Chemical Physics Letters 69, 185-189)NMR techniques.

Sample Preparation for Biocrates Life Sciences Absolute IDQ™ KitAnalysis

The Biocrates Life Sciences Absolute IDQ™ kit was used for EDTA plasmasamples as previously published (Römisch-Margl, W., C. Prehn, R.Bogumil, C. Röhring, K. Suhre, J. Adamski, Procedure for tissue samplepreparation and metabolite extraction for high-throughput targetedmetabonomics. Metabonomics, 2011. Online First). Well plate preparationand sample application and extraction were carried out according to themanufacturer's instructions. A final volume of 10 μl of plasma wasloaded onto the provided 96-well plate, containing isotopically labeledinternal standards. Liquid chromatography was realized on a DionexUltimate 3000 ultra high pressure liquid chromatography (UHPLC) system(Dionex AG, Olten, Switzerland) coupled to a 3200 Q TRAP massspectrometer (AB Sciex; Foster City, Calif., USA) fitted with a TurboVion source operating in electrospray ionization (ESI) mode. Sampleextracts (20 μl) were injected two times (in positive and negative ESImodes) via direct infusion using a gradient flow rate of 0-2.4 min: 30μl/min, 2.4-2.8 min: 200 μl/min, 2.9-3 min: 30 μl/min. MS sourceparameters were set at: desolvation temperature (TEM): 200° C., highvoltage: −4500 V (ESI −), 5500 V (ESI +), curtain (CUR) and nebuliser(GS1 and GS2) gases: nitrogen; 20, 40, and 50 psi; respectively,nitrogen collision gas pressure: 5 mTorr. MS/MS acquisition was realisedin scheduled reaction monitoring (SRM) mode with optimised declusteringpotential values for the 163 metabolites screened in the assay. Raw datafiles (Analyst software, version 1.5.1; AB Sciex, Foster City, Calif.,USA) were imported into the provided analysis software MetIQ tocalculate metabolite concentrations. List of all detectable metabolitesis available from Biocrates Life Sciences, Austria(http://biocrates.com).

Multivariate Data Analysis

The plasma NMR spectra were converted into 22K data points over therange of δ0.2-10.0 using an in-house developed MATLAB routine excludingthe water residue signal between δ54.68-5.10. Chemical shift intensitieswere normalized to the sum of all intensities within the specified rangeprior to chemometric analysis. Chemometric analysis was performed usingthe software package SIMCA-P+ (version 12.0.1, Umetrics AB, Umeå,Sweden) and in-house developed MATLAB (The MathWorks Inc., Natick,Mass., USA) routines. In order to detect the presence of similaritiesbetween metabolic profiles, Principal Component Analysis (PCA) (Wold,S., et al. (1987) Chemom. Intell. Lab. Syst. 2, 37-52), Projection toLatent Structures (PLS) (Wold, S., et al. (1987) PLS Meeting, Frankfurt)and the Orthogonal Projection to Latent Structures (0-PLS) (Trygg, J. &Wold (2003) J. Chemom. 17, 53-64) were used. Seven-fold cross validationwas used to assess the validity of the model (Cloarec, O., et al. (2005)Anal. Chem. 77, 517-526). The classification accuracy of the O-PLS-DAmodel was established from the predicted samples in the 7-foldcross-validation cycle.

Targeted MS data was analyzed by Random Forests by using the package‘randomForest’ (A. Liaw and M. Wiener (2002). Classification andRegression by random Forest. R News 2(3), 18-22.) running in the Renvironment (R Development Core Team (2011). R: A language andenvironment for statistical computing. R Foundation for StatisticalComputing, Vienna, Austria. ISBN 3-900051-07-0, URLhttp://www.R-project.org/.). Univariate significance tests forconfirmation were also performed in R.

Due to the non-normal distribution of the visceral adiposity, thefollowing parameters were employed for the subsequent metabolomicsanalysis: log-transform value of the visceral fat content, of theintraperitoneal/subcutaneous fat ratio (ratio 1), or of theintraperitoneal/abdominal fat ratio (ratio 2).

Anthropometric and biochemical characteristics of the cohort are shownin Table 1, as per stratification in four quartiles (Q1-4, n=10) basedon the log ₁₀ value of the intraperitoneal/abdominal fat ratio (ratio 2)measured using CT. Fasting glucose (p<0.10) and insulin (p<0.05), aswell as HOMA-IR (p<0.05) were higher in the subjects with the highestvisceral adiposity (Q4) compared to (Q1). Log-transform values of theintraperitoneal subcutaneous fat ratio or of theintraperitoneal/abdominal fat ratio were used preferably to stratifysubjects according to their visceral adiposity, since these parameterswere shown to be independent of BMI, Hipp, Waist, ALAT, MAP, andcalorimetric indices, which was not the case for log-transform value ofintraperitoneal fat volume. Interestingly in his cohort, HDL, LDL, andtotal cholesterol were not statistically different between groups.

In order to identify phenotypic signatures of visceral fat deposition,plasma samples were analyzed using ¹H-NMR and targeted LC-MS/MSmetabolomic approach. Analyses were conducted on the fasting plasmasamples. OPLS analysis of samples collected showed some subtle butsignificant associations between blood plasma lipids and visceral fatdeposition (R²X:0.68; R²Y:0.506; Q²Y:0.167). Random forest analysis wasalso employed to confirm the statistical association between specificplasma lipids and visceral fat status (FIG. 1), which suggested aspecific plasma lipid remodeling marked by changes inglycerophospholipids and the fatty acid saturation pattern.

Therefore, targeted LC-MS/MS metabonomics was employed to providestructural information and quantitative measures of 163 metabolites,including amino acids, sugars, acyl-carnitines, sphingolipids, andglycerophospholipids. Using OPLS analysis, it was possible to determinea metabolic signature of visceral fat adiposity (R2X:0.29; R2Y:0.68;Q2Y:0.32).

To select the more robust markers, there was used the % Mean decreaseaccuracy of ‘out-of-bag’ data as variable importance feature. In thisway, it was possible to determine the variables that better discriminatesubjects according to their visceral fat status (Q1 versus Q4). Both Q1,Q4 were assessed using either log-transform value of the intraperitoneal fat volume, ratio 1 and ratio 2. The modeling was also testedfor assessing inter-days metabolic variations, by considering each visitseparately (data not shown). Ultimately, 26 metabolites were retained asof importance to classify subjects according to their visceral fatadiposity (FIGS. 2, 3A, 3B, 3C. Visceral adiposity was associated withincreasing concentrations of circulating amino acids, includingglutamine, leucine/isoleucine, phenylalanine and tyrosine. Thesepatterns were associated with higher conentrations of acylcarnitines,including palmitoylcarnitine (C16), caproylcarnitine (C10)octenoylcarnitine (C8:1), and lysophospatidylcholine LPC 24:0 and diacylphospholipids, including PC 30:0, PC 34:4. In addition, visceraladiposity was marked by a depletion in acyl ethers PC-O 36:3, PC-O 40:3,PC-O 40:4, PC-O 40:6, PC-O 42:2, PC-O 42:3, PC-O 42:4, PC-O 44:3, PC-O44:4, PC-O 44:6, and two diacyl phosphopcholines (PC 42:0 and PC 42:2).To assess the individual discriminant ability of each component of thesignature, Wilcoxon Rank sum tests among the visceral fat adipositygroups were performed (all metabolites are listed in Table 2 accordingto the tested descriptor, namely log 10 value of ratio 2).

FIG. 2 summarizes the selected biomarkers together with their weight inthe classification of visceral adiposity, using log 10 value of visceralfat content, log 10 value of ratio 1 or log 10 value of ratio 2. Thesemarkers showed sensitivity and specificity of 0.90 for visceral fat incross-validation mode (Sencv, Specv).

TABLE 1 First Second Third Fourth Mann-Whitney Quartile QuartileQuartile Quartile P values Factor Q1 Q2 Q3 Q4 (Q1-Q4) Age, years 33.90 ±4.89 32.80 ± 3.58 38.00 ± 4.42 37.60 ± 5.82 0.13897 BMI, kg/m2 34.01 ±3.27 36.34 ± 3.62 37.00 ± 2.95 34.59 ± 4.42 0.93969 Log10intraperitoneal/ −0.70 ± 0.05 −0.61 ± 0.02 −0.52 ± 0.02 −0.40 ± 0.061.25506E−09 abdominal fat ratio Hipp, cm  122 ± 5.47  128 ± 7.48 127.34± 6.29  122.28 ± 9.65  0.56498 Waist, cm 97.28 ± 8.28 103.39 ± 8.7 108.72 ± 11.71 104.73 ± 13.84 0.45838 Waist/Hipp ratio  0.80 ± 0.07 0.81 ± 0.06  0.85 ± 0.07  0.84 ± 0.09 0.35104 Na, mmol/L 140.40 ± 1.35 140.80 ± 1.32  141.50 ± 1.58   139.9 ± 1.10  0.32894 K, mmol/L  4.05 ±0.18  4.10 ± 0.18  3.99 ± 0.25  4.04 ± 0.18 0.87656 Glucose, mmol/L 4.95 ± 0.35  5.17 ± 0.52  5.41 ± 0.49 5.37 ± 0.5 0.05716 Creatinine,mmol/L 65.60 ± 9.45  65.2 ± 11.2 64.78 ± 9.28  70.3 ± 6.53 0.2563Cholesterol, mmol/L  5.52 ± 1.01  5.58 ± 0.85  5.31 ± 0.68  5.48 ± 0.970.90965 HDL, mmol/L  1.54 ± 0.43  1.32 ± 0.29  1.38 ± 0.25  1.32 ± 0.240.18104 HDL/Chol ratio  3.77 ± 1.07  4.42 ± 1.22  3.99 ± 0.97  4.24 ±0.95 0.28901 LDL, mmol/L  3.50 ± 0.97  3.56 ± 0.88  3.34 ± 0.61  3.47 ±0.79 1 TG, mmol/L  1.04 ± 0.43 2.25 ± 2.1  1.28 ± 0.45  1.52 ± 0.570.09354 Urates, μmol/L 275.20 ± 41.93 263.22 ± 71.45 303.40 ± 75.28285.00 ± 31.70 0.35268 ASAT, U/L 21.40 ± 3.24  21.4 ± 4.48 24.00 ± 6.9424.50 ± 6.7  0.40157 ALAT, U/L 18.40 ± 6.11 19.20 ± 5.07 23.50 ± 8.34 27.10 ± 13.28 0.13971 ALAT/ASAT ratio  0.86 ± 0.25  0.91 ± 0.21 0.99 ±0.3  1.08 ± 0.34 0.12066 MAP, mmHg 57.80 ± 18.6  71.10 ± 19.75  62.40 ±20.97  57.80 ± 14.15 0.8796 GGT, U/L  20.00 ± 11.86 17.50 ± 6.88 21.10 ±4.84  25.44 ± 11.26 0.19122 Calorimetry, kcal/24 h 1357.00 ± 191.781434.00 ± 142.61 1469.00 ± 152.49 1433.00 ± 210.82 0.36362 Insulin 18.60± 9.21 22.12 ± 6.32 24.36 ± 7.22 25.44 ± 4.62 0.01468 HOMA-IR  4.24 ±2.02  4.95 ± 1.49  6.06 ± 1.87  6.12 ± 1.23 0.01149 NEFAs, μmol/L 544.50 ± 201.51  580.60 ± 301.38  596.20 ± 185.79  585.10 ± 188.620.66426

TABLE 2 First Second Third Fourth Mann-Whitney Quartile QuartileQuartile Quartile P values Metabolites Q1 Q2 Q3 Q4 (Q1-Q4) Glutamine,μmol/L 615.56 ± 107.95  748 ± 193.49  792.1 ± 260.61   714 ± 94.030.02468 Tyrosine, μmol/L 61.97 ± 11.02 80.54 ± 22.21 75.91 ± 21.83 80.99± 24.69 0.05347 Caproylcarnitine, μmol/L 0.22 ± 0.1   0.2 ± 0.09 0.14 ±0.06  0.3 ± 0.19 0.40018 Palmitoylcarnitine, μmol/L 0.07 ± 0.02 0.07 ±0.03 0.07 ± 0.03  0.1 ± 0.04 0.12065 Octenoylcarnitine, μmol/L 0.04 ±0.02 0.05 ± 0.02 0.05 ± 0.04 0.05 ± 0.02 0.25258 LPC 24:0, μmol/L 0.36 ±0.25 0.51 ± 0.24 0.52 ± 0.36 0.46 ± 0.31 0.21613 PC 30:0, μmol/L 4.43 ±1.48 5.17 ± 2.35 5.75 ± 1.98 5.57 ± 1.76 0.1564 PC 34:4, μmol/L  1.3 ±0.46 1.53 ± 1.14 1.41 ± 0.52 1.55 ± 0.75 0.31537 PC 42:0, μmol/L 0.65 ±0.23 0.48 ± 0.16 0.47 ± 0.08 0.48 ± 0.14 0.07889 PC 42:2, μmol/L  0.2 ±0.06 0.19 ± 0.11 0.13 ± 0.05 0.17 ± 0.08 0.40018 PC-O 34:1, μmol/L 9.94± 2.22 9.78 ± 3.84 8.48 ± 2.15 8.53 ± 0.99 0.17752 PC-O 34:2, μmol/L10.66 ± 3.5  9.31 ± 3.51 9.38 ± 4.57 8.77 ± 1.76 0.21102 PC-O 36:2,μmol/L 11.29 ± 2.64  11.86 ± 2.68  10.38 ± 3.08  9.17 ± 2.09 0.07865PC-O 36:3, μmol/L 7.04 ± 1.68  6.7 ± 2.61 7.11 ± 1.82  5.5 ± 1.240.02792 PC-O 40:3, μmol/L 1.41 ± 0.27 1.46 ± 0.38 1.27 ± 0.3  0.86 ±0.42 0.00421 PC-O 40:4, μmol/L 2.79 ± 0.56  2.9 ± 0.73 2.47 ± 0.69 2.02± 0.83 0.01784 PC-O 40:6, μmol/L 3.81 ± 0.86 3.27 ± 1.09  2.8 ± 0.842.74 ± 1.09 0.06525 PC-O 42:2, μmol/L 0.66 ± 0.23 0.56 ± 0.14 0.53 ±0.16 0.45 ± 0.18 0.05347 PC-O 42:3, μmol/L 0.89 ± 0.2  0.92 ± 0.14  0.9± 0.27 0.63 ± 0.26 0.06525 PC-O 42:4, μmol/L 1.34 ± 0.33 1.09 ± 0.281.09 ± 0.37 0.82 ± 0.22 0.00298 PC-O 44:3, μmol/L 0.21 ± 0.06  0.2 ±0.04 0.15 ± 0.06 0.17 ± 0.05 0.1564 PC-O 44:4, μmol/L 0.8 ± 0.3 0.67 ±0.24 0.63 ± 0.19 0.51 ± 0.18 0.01721 PC-O 44:5, μmol/L 2.29 ± 0.74 2.03± 0.55  1.9 ± 0.74 1.71 ± 0.7  0.04113 PC-O 44:6, μmol/L 1.52 ± 0.561.22 ± 0.3  1.11 ± 0.5  1.03 ± 0.32 0.01013 Phenylalanine, μmol/L  49.9± 14.16 50.47 ± 8.45  62.82 ± 22.17 56.42 ± 8.38  0.04113 Leucine +Isoleucine, 181.44 ± 53.02  214.2 ± 56.71 202.4 ± 27.39 228.8 ± 33.830.04536 μmol/L

What is claimed is:
 1. A method of diagnosing the effect of a change inlifestyle on visceral adiposity in a subject, comprising determining alevel of PC-O 42:4 in a body fluid sample previously obtained from asubject to be tested after the change in lifestyle, and comparing thesubject's PC-O 42:4 level to a predetermined reference value, whereinthe predetermined reference value is based on a PC-O 42:4 level in thesame body fluid obtained from the same subject prior to the change inlifestyle, and wherein an increased PC-O 42:4 level in the samplecompared to the predetermined reference value indicates a positiveeffect of the change in lifestyle on visceral adiposity.
 2. The methodaccording to claim 1, wherein the change in lifestyle is a change indiet of the subject.
 3. The method according to claim 2, wherein thechange in diet is at least one nutritional product that was previouslynot consumed or consumed in different amounts.
 4. The method inaccordance with claim 2, to test the effectiveness of a new nutritionalregiment.
 5. A method for diagnosing the effect of a change in diet onvisceral adiposity in a subject, comprising determining the level ofPC-O 42:4 in a body fluid sample previously obtained from a subject tobe tested after the change in diet, and comparing the subject's PC-O42:4 level to a predetermined reference value, wherein the predeterminedreference value is based on a PC-O 42:4 level in the same body fluidobtained from the same subject prior to the change in diet, and whereinan increased PC-O 42:4 level in the sample compared to the predeterminedreference value indicates a positive effect of diet change on visceraladiposity.
 6. The method according to claim 5, wherein the change indiet is at least one nutritional product that was previously notconsumed or consumed in different amounts.
 7. The method according toclaim 5, wherein the method serves to detect the effectiveness of a newnutritional regimen.